Sleeping Well Can Signal Health Issues You Wouldn’t Expect

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If you're one of nature's great sleepers, capable of snoring through hurricanes, the Superbowl, or an eight-hour flight, doubtless you thank the stars for your talent on a regular basis. However, while for a lot of us deep, regular sleep is a sign of health, sleeping well can also signal unexpected health issues — particularly if the sleep change comes on all of a sudden, or if you find yourself more tired in the day.

Sleep has a strong link with the rest of human health, and most medical concern centers on people who aren't getting enough sleep. "Sleep deficiency is linked to many chronic health problems, including heart disease, kidney disease, high blood pressure, [...] and depression," says the National Heart, Lung and Blood Institute. However, too much sleep or sleep that's deeper than usual can also mean all is not quite right.

Healthy sleep isn't static. It cycles through various phases throughout the night, from light non-REM (rapid eye movement) sleep down to deep non-REM sleep and, eventually, REM sleep, which is when dreaming occurs. Waking tends to occur in the lightest sleep period. Deep sleep, meanwhile, is associated with memory retention and muscle and cell repair. The optimal amount of sleep is about seven to nine hours for adults, says the National Institute of Health, though that changes as we age and we often sleep less.

Suddenly sleeping like a log? While it may feel good in the moment, it could also be a signal that you have a health issue that needs to be addressed. Keep a diary of your sleeping and make note if you have any other symptoms happening — it could help your doctor figure out what's up.

1. Depression

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Fatigue and excessive sleep are strongly associated with depression. Both insomnia and sleeping too much are recognized signals of a depressive episode, and it's common for people with depression to say it's "hard to get out of bed". Part of that is psychological, based on lowered mood, but part of it, research reveals, is also in how depression affects sleep.

Neuroscientist Patrick McNamara, writing for Psychology Today, explained that science has shown people with depression tend to have more REM phases in their sleep than people who don't have depression. "REM (rapid eye movement) sleep abnormalities are prime candidate sources of depression symptomology," he writes. A study in 2016 found that disturbed REM is linked to depression, and the researcher Rosalind D. Cartwright has discovered that in people with depression, REM sleep begins far earlier in the night and can be "abnormally long". Sleeping a lot and having odd dreams? Depression might be a possible explanation.

2. Type 2 Diabetes

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"Oversleeping is associated with many health problems, including Type 2 diabetes," Johns Hopkins Medicine wrote. A 2015 study showed that there appears to be a link between sleeping a lot and type 2 diabetes in women, though it's not clear whether it's cause or effect. “If you forced yourself to sleep less than 6 hours a night because you had too much going on, that’s one thing. But it’s another if you start sleeping longer spontaneously," neurologist Carl Bazil tells Everyday Health. If you're suddenly requiring more sleep and there are no obvious triggers, like new medication, then it's worth seeing a doctor.

3. Heart Issues

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If you sleep deeply and tend to rest for more than eight hours at a time, you're at increased risk of cardiovascular issues, according to a study published in the European Heart Journal at the end of 2018. "Both shorter (less than six hours a day) and longer (more than eight hours a day) estimated total sleep durations were associated with an increased risk" of cardiovascular issues and mortality, the study said. Underlying heart disease has been linked to sleepiness and excessive fatigue before, so if you suddenly sleep for a million years, particularly if you have a family history of cardiovascular problems, it's a notable symptom.

4. Hypothyroidism

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Sleeping deeply every night, along with other symptoms, can be a symptom of hypothyroidism, or an underactive thyroid. Thyroids control the metabolism, and one that's under-performing causes it to slow, creating symptoms like fatigue and joint pain. "Extreme tiredness, fatigue, and just feeling wiped out — these are common symptoms of an underactive thyroid gland," explains Everyday Health. Fatigue isn't the sole sign of hypothyroidism, so if you're just sleeping deeply and don't have any other symptoms, this is unlikely to be your issue.

5. Stress

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While stress is most notable for causing sleep disturbances and insomnia, in some of us it can go the other direction — and make us drop off. The phenomenon may simply be an energy-saving technique. Psychologist Dr. Curtis Reisinger told The Cut, “[...] one of the reasons that people sometimes get so wiped out and even fall asleep is that whenever you’re put up to a lot of mental tasks or physical tasks, it uses up glucose in the brain. Glucose is essentially sugar, and it gives you the energy you need." Depleted glucose means fatigue and deep sleep. If you're stressed at work and still get eight hours every night, it could be explained pretty simply: your brain's going into recovery mode.

While deep, regular sleep is most often a sign of health, it can also be a symptom of underlying disorders. Concerned that you're sleeping too much or your sleep has changed for unknown reasons? It's a good idea to visit a sleep specialist or your GP.